Chorionic villus sampling (CVS) is a valued method of prenatal diagnosis. The proposed study will address several aspects of the recent suggestions that the CVS-exposed infant has an increased likelihood of having limb and other defects, such as hemangiomas. We propose 3 major activities: 1) To determine from the findings in cohort studies of CVS-exposed pregnancies the spectrum of major malformations and serious birth marks which have been identified. Then, to recruit and evaluate 100 CVS-exposed children and 100 matched comparison children. The examiner will be unaware of the exposure status of the child. The purpose is to determine whether there is any specificity to the limb defect or other defects. At least 15 trips will be made to examine "blindly" CVS-exposed children with limb and other defects and a comparison group to determine whether there is a distinctive pattern of major and minor abnormalities in the CVS-exposed children. If there is "specificity" to the CVS-associated abnormalities, this will facilitate the comparison of the frequency of the same type of abnormality among unexposed children. 2) To determine among 158,000 infants (unexposed to CVS) born at Brigham and Women's Hospital (BWH) over an 18-year period the frequency of all types of limb deficiencies. To work with investigators in Sweden, British Columbia and Italy to determine the frequency of similar phenotypes and apparent etiologies for limb defects in their large epidemiologic studies. (3) To carry out a meta-analysis of the association of CVS with oromandibular-limb hypogenesis, unilateral forearm and hand "amputation" and terminal transverse limb defects as well as the occurrence of other birth defects. This analysis will be performed on the findings in both published and unpublished cohort and case-control follow-up studies of CVS-exposed infants. The unexposed comparison groups will be the unexposed infants surveyed at BWH and in three other separate studies. The meta-analysis will determine the range of the risk of malformations separately for gestational weeks 7 to 12 and will also assess the correlation of the week of exposure with the severity of the malformations. It will also assess the correlation of the abnormalities with the type of catheter used and the experience of the operator. An Advisory Committee will be established to review annually the findings from all projects. The findings in these projects will be of practical value to pregnant women, as well as to obstetricians and genetic counselors.